Geochemistry and Genesis of Oil and Gas Seeps in the Junggar Basin, NW China: Implications for Hybrid Petroleum Systems

Figure 5

Plots of selected molecular geochemical parameters for oil-seep, crude-oil, and source-rock samples from the northwestern Junggar Basin. (a) δ¹³C (in ‰ relative to the VPDB standard) vs. SA/SARA; (b) C₁₉T/C₂₀T vs. C₂₄Te/C₂₆T; (c) C₂₀T/C₂₁T vs. C₂₁T/C₂₃T; (d) Ts/Tm vs. G/C₃₀H; (e) C₂₉H/C₃₀H vs. C₃₅S/C₃₄S; (f) C₂₇/C₂₈ααα20R vs. C₂₈/C₂₉ααα20R; (g) C₂₉ααα20S/(20R+20S) vs. C₂₉αββ/(αββ+ααα); (h) C₂₄Te/C₃₀H vs. Dia/Reg. Abbreviations: SA = saturates+aromatics in %; SARA = saturates+aromatics+resins+asphaltenes in %; T = tricyclic terpane; Te = tetracyclic terpane; G = gammacerane; H = hopane; S = 22S hopane; Dia = diasteranes; Reg = regular steranes. Data from Table 2.

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